chore: P1 工程化工具链

- pyproject.toml：pytest/black/isort/mypy 统一配置
- requirements-dev.txt：测试与代码规范开发依赖
- .flake8 / .editorconfig：PEP8 与编辑器统一
- .pre-commit-config.yaml：提交前钩子
- Makefile：常用命令集
- .env.example：环境变量模板（76 键）
- tests/：pytest 骨架 + R 响应格式冒烟测试

Co-Authored-By: Claude <noreply@anthropic.com>

tests/unit/__init__.py

@@ -0,0 +1 @@
+"""单元测试包。"""

tests/unit/test_core/__init__.py

@@ -0,0 +1 @@
+"""core 层单元测试。"""

tests/unit/test_core/test_response.py

@@ -0,0 +1,53 @@
+"""
+R 统一响应格式单元测试
+
+验证 `R.ok()` / `R.failed()` 返回的 JSON 响应结构符合前后端约定：
+{code, data, msg, ok}（code=0 成功，非 0 失败）。
+"""
+
+from utils import R
+
+
+class TestOk:
+    """成功响应"""
+
+    def test_ok_default_format(self):
+        resp = R.ok()
+        body = resp.get_json()
+
+        assert body["code"] == 0
+        assert body["ok"] is True
+        assert body["data"] is None
+        assert body["msg"]
+
+    def test_ok_with_data(self):
+        resp = R.ok(data={"id": 1, "name": "张三"})
+        body = resp.get_json()
+
+        assert body["code"] == 0
+        assert body["data"] == {"id": 1, "name": "张三"}
+
+    def test_ok_with_kwargs(self):
+        resp = R.ok(data=[], total=100)
+        body = resp.get_json()
+
+        assert body["total"] == 100
+
+
+class TestFailed:
+    """失败响应"""
+
+    def test_failed_default_format(self):
+        resp = R.failed()
+        body = resp.get_json()
+
+        assert body["code"] != 0
+        assert body["ok"] is False
+        assert body["data"] is None
+
+    def test_failed_custom_code(self):
+        resp = R.failed(msg="未授权访问", code=401)
+        body = resp.get_json()
+
+        assert body["code"] == 401
+        assert body["msg"] == "未授权访问"